1. Field of the Invention
This invention relates to a method of protecting crops and more particularly, it is concerned with a method of protecting crops, whereby the protecting effect can be maintained in stable manner for a long time by the use of a non-toxic and stable composition containing cinnamic aldehyde as a predominant component.
2. Description of the Prior Art
Cinnamic aldehyde is a non-toxic material described in the official document as a food additive, which is represented by the following chemical structural formula: ##STR1## The inventor has noted that cinnamic aldehyde has an excellent microbe controlling effect and can favorably be applied to protection of crops and has thus proposed a method of protecting crops characterized by spraying an emulsion of cinnamic aldehyde on the crops and thus protecting the crops from insect pests, microorganisms and pathogenic microbes, as disclosed in Japanese Patent Publication No. 25682/1986. In this method, an emulsion of cinnamic aldehyde, for example, emulsified with a nonionic surfactant consisting of a condensate of ethylene oxide and propylene oxide is sprayed on crops to protect from molds such as ascomycetes, deuteromycetes, etc., pathogenic microbes such as phycomycetes, basidiomycetes, bacteria, etc. and insect pests such as cockroach carrying virus pathogenic microbes. This method is particularly effective for preventing economical loss due to damage by blight and noxious insects in the harvesting season for the health care of producers and for the preventive maintenance of soils.
Furthermore, the inventor has also proposed a method of protecting crops, characterized by applying a fertilizer with cinnamic aldehyde or a cinnamic aldehyde derivative to the soil, as disclosed in Japanese Patent Publication No. 32283/1986. This method is a novel and effective fertilizing method wherein the soil is fertilized with a fertilizer with cinnamic aldehyde or its derivative such as halogen derivatives thereof and thus subjected to disinfection in non-toxic manner while inhibiting harmful microbes without affecting useful bacteria, thereby maintaining a B/F value well-balanced.
Cinnamic aldehyde is a material which is non-toxic and has an excellent microbe controlling effect, but on the other hand, the stability of the microbe controlling effect is insufficient and the cause thereof has not been made clear, as described in Japanese Patent Application OPI (Kokai) No. 52236/1975 relating to a method of protecting foods with cinnamic aldehyde and a liquid bulb product. For the protection of crops, however, the stability of this effect for a long time has particularly been desired. Since cinnamic aldehyde has widely been used as a spice for foods, but has not been used for the protection of crops until the inventor has proposed, study of the stability for a long period of time has not been made.